With advances in wireless communication technology, it has become possible to popularize information communication terminals such as mobile telephones, PDA's, GPS receivers, etc. In such information communication terminals, small-size, light-weight, thin and flat patch antennae are mainly used.
In general, the size of a patch antenna is proportionate to design frequency. Consequently, in order to produce a patch antenna that is able to generate polarized waves of the same frequency band and that is of a smaller size, a dielectric substrate having a high dielectric constant should be used.
However, using a dielectric having a high dielectric constant degrades the radiating characteristics of the antenna, resulting in lower profits and higher production costs, as well as lower production yield. Consequently, there is a limit to how far the size of an antenna may be reduced with the use of a dielectric having a high dielectric constant. Accordingly, there are on-going attempts through structural changes to produce patch antennae having a high design frequency band while having a small size.
At the same time, a patch antenna according to the related art makes right-handed circular polarized waves (RHCP) or left-handed circular polarized waves (LHCP) by changing the feeding position on the patch surface or the patch structure. Here, transmission and reception are achieved between patch antennae of the same rotational direction (RHCP or LHCP).
However, in areas such as inside a tunnel where the signal's line of sight (LOS) is not guaranteed, due to the fading phenomenon, linear polarized waves need to be received with the use of a patch antenna that generates circular polarized waves. Here, a wave loss of −3 dB occurs, creating a problem of not being able to receive signals efficiently.
The above information disclosed in the Background Art section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.